- Documentation/{Extensions,SwiftUI,UIKit}.md shells with category headings + TOC
- README: Documentation table linking all 4 guides
- footer: drop the second github badge, keep the resume link
- Package.swift: .iOS(.v13) -> .iOS(.v15), .watchOS(.v6) -> .v8
(README already stated iOS 15; watchOS 8 needed for URLSession.upload(for:fromFile:))
- drop the iOS-13 uploadTask continuation bridge; both upload overloads now
share one runUpload using session.upload(for:fromFile:delegate:)
- remove now-redundant @available(iOS 15) from the progress overload and test
- Documentation/API.md: drop iOS-version caveats
